虫瘿与其生物群落及寄主植物间的关系

虫瘿是自然界极其常见的生物现象,是植物与昆虫互作的奇特产物。本文对虫瘿生物群落多样性、虫瘿与其生物群落的关系以及虫瘿与寄主植物的关系进行概述,探讨了致瘿昆虫在虫瘿形成中的作用、植物化学对致瘿昆虫产卵交配行为的影响以及植物激素在虫瘿形成中的作用,最后对虫瘿今后的研究方向进行了讨论,为虫瘿的致瘿生物学及其瘿内生物相互关系的进一步研究奠定基础。     

环境温度对社鼠能量需求和食物同化的影响

Niviventer confucianus is a common species of rodent in South China. We designed an experimental protocol to determine the influence of temperature on energy requirement and food assimilation of the N. confucianus . In our feeding trials, four experimental temperatures were applied: 17℃,22℃,27℃ and 32℃. The energy requirements of N. confucianus under different temperature were:107 43±6 44 KJ/animal/day (17℃),94 76±4 46 KJ/animal/day (22℃),73 96±5 65 KJ/animal/day(27℃),and 62 80±5 15 KJ/animal/day(32℃),respectively. Moreover, the energy intake, digested and assimilated energy of N. confucianus decreased with temperature increase. However, no significant differences on digestibility and assimilation rate of N. confucianus were found among four experimental temperatures. It indicated that, during a range of particular temperatures, N. confucianus might maintain relatively high digestibility by change of digest tract morphology.     

Phylogeny of Rhus gall aphids (Hemiptera : Pemphigidae) based on combined molecular analysis of nuclear EF1α and mitochondrial COII genes

Rhus gall aphids (Fordinae : Melaphidini) have a disjunct distribution in East Asia and North America and have specific host plant relationships. Some of them are of economic importance and all species form sealed galls which show great variation in shape, size, structure, and galling‐site. We present a phylogeny incorporating ten species and four subspecies of Rhus gall aphids based on 1694 base pairs of nuclear elongation factor‐1α (EF1α) and mitochondrial cytochrome oxidase subunit II (COII) DNA sequence data. The results suggest that Melaphidini is monophyletic and at the genus level, Schlechtendalia, Nurudea, and Floraphis were each monophyletic. Kaburagia and Meitanaphis were not monophyletic and therefore inconsistent with the current classification. The North American sumac gall aphid, Melaphis rhois, was most closely related to the East Asian Floraphis species, although this was poorly supported. The conservation of gall morphology with respect to aphid phylogeny rather than their host plants suggests that gall morphology is largely determined by the aphids. While there is no evidence of strict co‐speciation between the aphids and their primary host plants, switching between recently diverged host plants may be involved in the speciation process in Melaphidini.     

Agrobacterium radiobacter strains K84, K1026 and K84 Agr‐ produce an antibiotic‐like substance,active in vitro against A. tumefaciens and phytopathogenic Erwinia and Pseudomonas spp.

Agrobacterium radiobacter strains K84, K1026 and K84 Agr^‐ produced in vitro an antibiotic‐like substance (ALS 84), different from agrocin 84 and observed in mannitol‐glutamate medium. Twenty five out of 39 A. tumefaciens strains of biovars 1, 2 and 3 were sensitive to ALS 84 regardless of their sensitivity to agrocin 84. Sensitivity in A. tumefaciens strain C58 was not encoded by the Ti‐plasmid. Most isolates tested of Erwinia carotovora subsp. carotovora E. carotovora subsp. atroseptica, Pseudomonas corrugata P. cichorii and unidentified isolates from galls were also sensitive to this substance. ALS 84 was not affected by the proteases studied, nor by treatment at 62°C for 30 min and had a bacteriostatic effect. The production of ALS 84 might play a role in the complex mechanism of biological control of crown gall, especially in strains resistant to agrocin 84 and sensitive to ALS 84, and by the creation of an ecological niche favourable to A. radiobacter strains K84, K1026 or K84 Agr^‐.     

COMPARATIVE ANALYSIS OF GALL MORPHOLOGY IN AUSTRALIAN GALL THRIPS: THE EVOLUTION OF EXTENDED PHENOTYPES

We used a combination of morphometric, phylogenetic, and life-history information to analyze the evolution and possible adaptive significance of gall morphology in a clade of 24 species of gall-inducing thrips (Insecta: Thysanoptera) on Australian Acacia trees. Principal components analysis revealed that galls varied in morphology along two main axes, spherical versus elongate (PC1) and general size (PC2). A high degree of conservation of gall shape on an independently derived phylogeny of the insects and the presence of nine species of Acacia each bearing two or three morphologically disparate gall forms induced by different thrips species indicate that interspecific variation in gall form is determined predominantly by the insects. Character optimization of PC1 on the phylogeny of gall thrips suggested that the ancestral gall form was a simple roll or curl. The diversification of gall form involved four main processes: (1) the convergent evolution of relatively spherical galls in two clades; (2) the evolution of small elongate and hemispherical galls in one clade; (3) the evolution of a lobed interior in a species with a spherical gall and multiple within-gall generations; and (4) the evolution of intraspecific gall polymorphism in a clade of apparent sibling species. Comparative analyses indicated that gall sphericity was associated with the presence of physogastry (foundress hyperfecundity) and that small elongate and hemispherical forms may be associated with the presence of multiple generations in a gall and, perhaps, with the presence of soldier castes. The evolution of a lobed interior in one species, which greatly increases inner surface area, coincided with the evolution of multiple generations. In the clade with intraspecific gall polymorphism in some species, patterns of intraspecific variation mirror patterns of interspecific variation within the clade as a whole. This is the first study to analyze the evolution of gall size and shape in a phylogenetic context and to investigate the life-history correlates of evolutionary changes in gall form. Taken together, our findings indicate that the main selective pressures driving the evolution of gall form in Australian gall thrips on Acacia involve inner surface area to volume relationships, which change in concert with foundress fecundity and the number of within-gall generations.     

桉树枝瘿姬小蜂胚胎发育及胚后发育

【目的】对桉属树木的重要害虫桉树枝瘿姬小蜂Leptocybe invasa胚胎发育及胚后发育生物学特征进行详细调查,以期深入了解该害虫的生物学特征及发生为害规律。【方法】对桉树枝瘿姬小蜂雌性生殖系统、卵、虫瘿进行解剖,观察其胚胎发育和胚后发育过程,测量其各发育阶段的虫瘿、虫室和幼体的体积及薄壁细胞层的厚度。【结果】桉树枝瘿姬小蜂完成胚胎发育约需138 h,由3个阶段组成：产卵后0-24 h为营养物质聚集期;36-84 h为胚胎期;96-138 h为孵化期。桉树枝瘿姬小蜂在虫瘿内完成发育,其发育过程与虫瘿发育过程保持一致。虫瘿结构由3个基本层组成,由外至内分别为表皮层、中间层和薄壁细胞层。桉树枝瘿姬小蜂幼虫体积增长速率随发育时间呈现单峰型,在30 d时增长速率达到最大;虫瘿体积的增长速率呈抛物线状,并且虫瘿内薄壁细胞层厚度随发育时间也呈现抛物线状,其前期增长较快,后期下降变缓。【结论】桉树枝瘿姬小蜂发育至25 d时处于取食量较小的低龄阶段,而虫瘿内薄壁细胞层(食物)厚度已达到最大,为幼虫体积快速增大阶段作好准备。     

Expression of Rice Gall Dwarf Virus Outer Coat Protein Gene (S8) in Insect Cells

To obtain the P8 protein of Rice gall dwarf virus (RGDV) with biological activity,its outer coat protein gene S8 was expressed in Spodoptera frugiperda (Sf9) insect cells using the baculovirus expression system.The S8 gene was subcloned into the pFastBacTM1 vector,to produce the recombinant baculovirus transfer vector pFB-S8.After transformation,pFB-S8 was introduced into the competent cells (E.coli DH10Bac) containing a shuttle vector,Bacmid,generating the recombinant bacmid rbpFB-S8.After being infected b...     

Genotypic characteristics of the causal agent of chinaberry gall

Chinaberry (Melia azedarach) is a deciduous tree of moderate size, grown throughout warm countries. The plantation of M. azedarach tree improves the environmental condition of the country. During the years 1390–1391, bacterial gall symptoms were observed on chinaberry. The isolation of the causal agent bacteria was done on nutrient agar medium. Approximately 4 weeks after inoculation, galls developed on the chinaberries inoculated with different isolates. The specific primer was designed based on 16S rRNA gene and all isolates amplified 429 bp fragment. To sequence 16S rRNA gene of Shiraz isolates, the universal primer PS16Sf-FAM/PS23Sr was used to amplify 16S rRNA gene. The Iranian isolates of Pseudomonas meliae showed 99.7% similarity to P. meliae (type strain) in the Gene Bank. Based on the rep-PCR results and sequence of 16S rRNA gene, Pseudomonas syringae and Pseudomonas fluorescens were placed in the different groups.     

Context‐dependent effects of mycorrhizae on herbivore density and parasitism in a tritrophic coastal study system

1. Stressful abiotic conditions and mycorrhizal fungi have both been shown to influence plant quality significantly, yet the interactive effects of these factors on relationships among plants, herbivores, and natural enemies remain unclear. 2. In this study, the results of a factorial field experiment are reported in which the effects of plant stress and mycorrhizae on density and parasitism of three herbivores of Baccharis halimifolia L. were examined. 3. Plant stress was increased by adding salt to the soil, and association with mycorrhizal fungi was increased by inoculating plant roots. 4. Inoculation with mycorrhizal fungi resulted in increased density of all three herbivore species, but the effects of mycorrhizae on parasitism varied by species and with soil salinity levels. For the gall maker Neolasioptera lathami Gagne, mycorrhizae decreased parasitism regardless of soil salinity levels. For the leaf miners Amauromyza maculosa Malloch and Liriomyza trifolii Burgess, mycorrhizae effectively negated the decrease in parasitism resulting from increased salinity. 5. The results of this study show that the effects of mycorrhizae on parasitism may be context dependent, and can be positive or negative depending upon species and environmental conditions.